The Cell Culture Core will provide scientific and technical support to the SCOR project by helping investigators implement and interpret the results of their hematopoietic cell culture experiments. The scientific and technical support will be provided in the following ways: a) The Project Leader of the Core unit will provide a centralized scientific and technical environment in which the scientists of this SCOR would be able to discuss and design the cell biology of their experimental plans. She will also provide experimental training in cell culture procedures to investigators who feel that the experiments should be carried out in their own laboratories. b) The technical support of the Core will be: CD34+ isolation from hematopoietic tissues (cord blood, adult blood or marrow, fetal liver and fetal blood) from normal individuals or from individuals with a particular blood phenotype (for example, Kell-null using immunoaffinity chromatography (Cellpro devices). Cryopreservation and storage of such samples which cannot be processed immediately and maintaining records of the sample bank. Progenitor cell assay and liquid culture expansion of defined cell lineages (erythroid, myeloid and mast cells) under culture conditions which would allow the expansion of only one well defined differentiation lineage. The core will also establish and maintain stromal cell lines from normal bone marrow. Preparation of tested chemical and cellular reagents for primary hematopoietic cultures.